This application claims the benefit of Japanese Patent Application Number 2007-285435 which were filed on Nov. 1, 2007, the entirety of which is incorporated by reference.
1. Field of the Invention
This invention relates to a router which comprises a base, a pair of guide shafts stood on the base and a main body mounted with a tool pointed downward at an underside thereof, the main body being coupled to the pair of guide shafts in such a manner that the main body is movable upward and downward.
2. Description of Related Art
In the router, typically, for example as disclosed in Japanese Laid-Open Patent Application, Publication No. 6-328402, a pair of columns (guide shafts) are stood on a disk-shaped base, and a main body having a motor housed therein and a downward-pointing tool mounted on an underside thereof is provided with sleeve-like bushings in which the columns can be loosely fitted. The bushings of the main body support the columns whereby the main body is coupled to the columns slidably upward and downward along the columns. A biasing device such as a coil spring is provided between the base and the main body to bias the main body upward. In the normal state, the main body is positioned at an upper-limit position by the biasing device, and is operable to be moved down by means of handles provided on the main body. In operation, thus, an operator sets the base on a workpiece and then lowers the main body by manipulating the handles so that the tool passes through the base to thereby cut the workpiece placed under the base.
The main body of the router constructed as described above is configured to be movable upward and downward with the help of the sleeve-like bearings (bushings) which support the columns. As a result, a friction between the columns and the bushings would possibly hamper a smooth upward and downward movement of the main body in some instances. In particular, when an operator attempts to lower the main body with one hand gripping one of the handles, the main body would be swayed and blocked from moving any longer, which would thus impair the ease of operation of the router. Furthermore, the presence of the backlash structurally inevitably produced between the columns and the bushings would disadvantageously reduce the cutting precision.
Therefore, it would be desirable to provide a router of which a main body is smoothly operable even with one hand when the router is to be moved upward or downward and which is configured to reduce or eliminate the backlash between its guide shafts and bushings provided in the main body, so that the ease of operation and the cutting precision may be improved.
The present invention has been made in an attempt to eliminate the above disadvantages, and illustrative, non-limiting embodiments of the present invention overcome the above disadvantages and other disadvantages not described above. Also, the present invention is not required to overcome the disadvantages described above, and an illustrative, non-limiting embodiment of the present invention may not overcome any of the problems described above.